The present invention is related to a multi-stage transmission provided with plural planetary gear systems having different rotation ratios on the same axis in multi-stage. The invention enables interruption of transmission of rotation of an input shaft to an output shaft provided on the same axis, through one of a group of planetary gear systems having a prescribed speed change ratio.
Transmission by a planetary gear system has been widely used because it can produce a larger velocity ratio than transmission by other gear types. The conventional transmission of this type is designed, for example as disclosed in Japanese utility model application No. Hei. 6-18748, to fix an internal gear and to obtain a fixed velocity ratio through carriers arranged in multi-stage and a pinion gear and a sun gear.
In the case of forming a single multi-stage transmission by a gear transmitting system of a non-planetary gear type, there are such disadvantages as the body of the machine becomes large, the weight of the machine increases and the machine has inferior shock enduring capacity and wear resisting capacity. According to the conventional planetary gear system, it is possible to obtain a large speed change ratio on the same axis and to make the size of the machine compact, but there is the disadvantage that multi-stage change of speed is impossible.
For this reason, it has been a problem to produce a multi-stage transmission which has shock enduring capacity and a wear resisting capacity and which enables multi-stage changes of speed while utilizing the advantages of the planetary gear system and avoiding increasing the size of the machine body.